The Messenger of Allah ﷺ said, "Bilal does not know when night ends, so eat and drink until Ibn Umm Maktum calls the adhan."
حدثنا هاشم حدثنا عبد الرحمن عن زيد بن أسلم
أن رسول الله ﷺ قال إن بلالا لا يدري ما الليل فكلوا واشربوا حتى ينادي ابن أم مكتوم
Its isnad is sahih. As for this wording, "Bilal does not know when it is night," I have not found it anywhere other than this passage. The hadith of Ibn Umar on this subject is well known and recognized, "Bilal calls the adhan while it is still night," and so on, which has appeared several times before, including at 4551 and 5852, and among them is the hadith that follows this one, 6051.However, the meaning of this narration is supported by the hadith of Anas, which will come in the Musnad at 12455, as a saying of the Prophet, "Do not let Bilal's call to prayer keep you from your pre-dawn meal, for there is something wrong with his eyesight," and its isnad is sahih. It is also supported by the hadith of Samura bin Jundab, which will likewise come in the Musnad (5: p. 9), as a saying of the Prophet, "Do not be deceived by Bilal's call, for there is a defect in his eyesight."